# CVE-2026-76070: Netis NC63 V3.0.0.3327 Stack Buffer Overflow via Login Password Parameter

> Unauthenticated attackers can achieve remote code execution with root privileges via a stack buffer overflow in the login handler.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Aug 2026
- **Updated:** 24 Aug 2026
- **Also known as:** GHSA-7gc7-3gxp-v85m

## What is CVE-2026-76070?

CVE-2026-76070 is a critical memory corruption vulnerability in Netis Systems NC63, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Netis NC63 firmware through V3.0.0.3327 contains a stack-based buffer overflow vulnerability that allows unauthenticated remote attackers to overwrite saved stack state by submitting an oversized Base64-encoded password to the login handler in /bin/netis.cgi. Attackers can exploit the custom Base64 decoder's lack of output length validation against the fixed-size stack buffer to achieve remote code execution with root privileges, as the Boa web server executes the CGI environment as root.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-76070?


## How do I fix CVE-2026-76070?

No fix has been published for CVE-2026-76070 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76070 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-76070 exists.

Public exploit code:

- Original research and PoC for a pre-auth Base64-decoded password stack buffer overflow in Netis NC63 login.cgi (github_poc): https://github.com/ozcanpng/CVE-2026-76070

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76070 and fix it if it is affected.

What it is: CVE-2026-76070 is a critical memory corruption vulnerability in Netis Systems NC63, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-76070 exists.

Affected product: Netis Systems NC63. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-76070/ (Markdown: https://insights.sbomify.com/CVE-2026-76070/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76070
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76070
- OSV: https://osv.dev/vulnerability/CVE-2026-76070

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76070/
Summaries are generated and may contain mistakes; the official description above is the record.